The Short Message Service provided for communicating text messages between user equipment has proved to be one of the most utilised applications of the GSM system. Although an SMS message provides only a relatively low communications bandwidth, for non-real time data communications, the popularity of the SMS for text messaging has meant that a demand for the SMS is likely to remain, even though future generation mobile radio systems may offer higher bandwidth communications. Thus, although future generation mobile radio systems may support alternative access technologies, and therefore more a convenient data communications facility, there will exist a requirement to deliver SMS messages to user equipment, even though the user equipment may have a facility for communicating using these alternative access technologies. This is because SMS messages may be generated by SMS enabled user equipment from GSM or UMTS networks.